On the space maps the Empire has a pop cap of 20, and the Rebels 25. Both the ISD and the Mon Cal cruiser are worth 4 a piece. Fighters cost 1 for the Rebels and are free for the Imperials. Other than that, most ships cost 2-3 each.
I'm not sure exactly how many stormtroopers there are in each unit in EaW, but ground battles have a total pop cap of 10 for each side. A unit of stormtroopers (2 squads of probably 20-25 soldiers in each) costs 1.
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